1. Field of the Disclosure
This invention is related to image sensors, and more particularly, to color filter arrays for use in color image sensors.
2. Background
Image sensors have become ubiquitous. They are widely used in digital still cameras, cellular phones, security cameras, as well as, medical, automobile, and other applications. The technology used to manufacture image sensors, and in particular, complementary metal-oxide-semiconductor (CMOS) image sensors (CIS), has continued to advance at a great pace. For example, the demands for higher resolution and lower power consumption have encouraged the further miniaturization and integration of these image sensors.
Conventional CMOS image sensors use color filter arrays to help capture color information. A color filter array includes a pattern of different colored filters to filter the light that reaches each pixel cell in an underlying color image sensor. In conventional color filter arrays, the thicknesses of the color filters vary differently within a wafer, which causes variations in color shading at different locations in the image sensor. These undesired color variations resulting from the non-uniform thicknesses in the color filter array degrade the quality of images that are captured by the color image sensor.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.